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<jats:p>Ways on energy enhancement for single frequency oscillator are reported in this paper. By quantitative analysis on gain and loss coefficients for each cavity mode with inserted etalons, a 37 mJ, 100 Hz high energy single-frequency Nd:YAG oscillator is obtained. The pulse energy is promoted by enhancement of nearly 7 times for a single frequency oscillator reported. The result proves that this method does help for energy enhancement. It has attractive potential for high energy single frequency oscillator design, especially on condition of intensive side pumped or long cavity laser, where strong competitors exist and are hard to be suppressed.</jats:p>

<jats:p>Bound states can be supported on the surface of a periodically corrugated perfect conductor known as spoof surface plasmon polaritons with their dispersion curves reside below the light line. Here we show that bound states in the continuum (BICs) can also be achieved in such systems. Two types of grating structures are proposed to suppress the radiation leakage and hence generate bound states. The first one is a simple grating with broad grooves in which multiple cavity modes are accommodated. Due to the symmetry incompatibility and the destructive interaction mainly from the TM<jats:sub>0</jats:sub> and TM<jats:sub>1</jats:sub> modes, BICs at the <jats:italic>Γ</jats:italic> point and at off-<jats:italic>Γ</jats:italic> points are both realized. The second one is a dimerized grating with two grooves in each unit cell. The destructive interaction between the modes in the two grooves can suppresses the radiation and BICs at the <jats:italic>Γ</jats:italic> point are observed. The <jats:italic>Q</jats:italic> factors of the whole bands can be further tuned by the dimerization strength effectively. This work may offer new opportunity for the applications of metallic grating in the low frequency bands.</jats:p>

<jats:p>Owing to the unique feature that the signal and reference waves of self-interference digital holography (SIDH) contain the same spatial information from the same point of object, compared with conventional digital holography, the SIDH has the special spatial coherence properties. We present a statistical optics approach to analyzing the formation of cross-correlation image in SIDH. Our study reveals that the spatial coherence of illumination light can greatly influence the imaging characteristics of SIDH, and the impact extent of the spatial coherence depends substantially on the recording distance of hologram. The theoretical conclusions are supported well by numerical simulation and optical experiments.</jats:p>

<jats:p>Gain refinement in metal alloy can be achieved by applying an electric current pulse (ECP) in solidification process. Forced flow inside the melt has been proved to be a key role in grain refinement. In this paper, the fluid flow inside Ga 20 wt%–In 12 wt%–Sn alloy induced by a damping sinusoidal ECP flowing through two parallel electrodes into the cylindrical melt was investigated by both experimental measurements and numerical simulations. Experimental results showed that a strong descending jet was induced beneath the bottom of electrodes under the application of ECP. Besides, it was found that flow intensity increases with the increase of amplitude, frequency, and pulse width, respectively. In order to unlock the formation mechanism of flow pattern and the relevance of flow intensity varied with electrical parameters, a three-dimensional numerical model under the application of ECP was established. Meanwhile, a comparative study was conducted by numerical simulations to reveal the distributions of electromagnetic fields and forced flow. Numerical results showed that the downward Lorentz force induced by ECP was concentrated beneath the bottom of electrodes. This downward Lorentz force induces a descending jet and provokes a global forced flow. According to numerical simulations, the evolution of flow intensity with electrical parameters under the application of ECP can be understood by the time averaged impulse of Lorentz force.</jats:p>

<jats:p>Different C<jats:sub>60</jats:sub> crystals were synthesized by precipitation from a mixture of the good solvent m-xylene and the poor solvent isopropyl alcohol. The samples were characterized by scanning electron microscopy (SEM), Raman spectroscopy, thermogravimetric analysis, and high resolution transmission electron microscope (HRTEM). We found that the morphologies and sizes of the samples could be controlled by adjusting the volume ratio between the good and poor solvents. Especially, an unexpected short flower column-like crystal was synthesized at low ratios (from 1:6 to 1:12). Room temperature photoluminescence (PL) and HRTEM studies of the C<jats:sub>60</jats:sub> crystal samples reveal that the PL efficiency of the crystals decreases with increasing crystalline order and that the disordered C<jats:sub>60</jats:sub> crystals synthesized at the ratio of 1:2 show 10 times higher PL efficiency than that of pristine C<jats:sub>60</jats:sub>. The mechanism of the growth process of these C<jats:sub>60</jats:sub> crystals was also studied by replacing the good solvents m-xylene with toluene and mesitylene.</jats:p>

<jats:p>Fe-Cr ferritic/martensitic (F/M) steels have been proposed as one of the candidate materials for the Generation IV nuclear technologies. In this study, a widely-used ferritic/martensitic steel, T91 steel, was irradiated by 196-MeV Kr<jats:sup>+</jats:sup> ions at 550 °C. To reveal the irradiation mechanism, the microstructure evolution of irradiated T91 steel was studied in details by transmission electron microscope (TEM). With increasing dose, the defects gradually changed from black dots to dislocation loops, and further to form dislocation walls near grain boundaries due to the production of a large number of dislocations. When many dislocation loops of primary <jats:italic>a</jats:italic> <jats:sub>0</jats:sub>/2〈 111 〉 type with high migration interacted with other defects or carbon atoms, it led to the production of dislocation segments and other dislocation loops of <jats:italic>a</jats:italic> <jats:sub>0</jats:sub> 〈 100 〉 type. Lots of defects accumulated near grain boundaries in the irradiated area, especially in the high-dose area. The grain boundaries of martensite laths acted as important sinks of irradiation defects in T91. Elevated temperature facilitated the migration of defects, leading to the accumulation of defects near the grain boundaries of martensite laths.</jats:p>

<jats:p>The defect evolution in InP with the 75 keV H<jats:sup>+</jats:sup> and 115 keV He<jats:sup>+</jats:sup> implantation at room temperature after subsequent annealing has been investigated in detail. With the same ion implantation fluence, the He<jats:sup>+</jats:sup> implantation caused much broader damage distribution accompanied by much higher out-of-plane strain with respect to the H<jats:sup>+</jats:sup> implanted InP. After annealing, the H<jats:sup>+</jats:sup> implanted InP did not show any blistering or exfoliation on the surface even at the high fluence and the H<jats:sub>2</jats:sub> molecules were stored in the heterogeneously oriented platelet defects. However, the He molecules were stored into the large bubbles which relaxed toward the free surface, creating blisters at the high fluence.</jats:p>

<jats:p>Integrating nanowires with nonuniform diameter and random spatial distribution into an array can afford unconventional and additional means for modulating optical response. However, experimental realization of such a nanowire array is quite challenging. In this work, we propose a new fabrication strategy which takes advantage of ion track technology, via sequential swift heavy ion irradiation and ion track etching. Based on this strategy, we unprecedentedly realize nanowire arrays, using gold as an example, with gradient and programmable diameters in a controlled manner. We further demonstrate that such nanowire arrays can support broadband, tunable, and enhanced plasmonic responses. We believe that our new type of nanowire arrays will find great potential in applications such as light management and optoelectronic devices.</jats:p>

<jats:p>The development of reliable fusion energy is one of the most important challenges in this century. The accelerated degradation of structural materials in fusion reactors caused by neutron irradiation would cause severe problems. Due to the lack of suitable fusion neutron testing facilities, we have to rely on ion irradiation experiments to test candidate materials in fusion reactors. Moreover, fusion neutron irradiation effects are accompanied by the simultaneous transmutation production of helium and hydrogen. One important method to study the He–H synergistic effects in materials is multiple simultaneous ion beams (MSIB) irradiation that has been studied for decades. To date, there is no convincing conclusion on these He–H synergistic effects among these experiments. Recently, a multiple ion beam <jats:italic>in-situ</jats:italic> transmission electron microscopy (TEM) analysis facility was developed in Xiamen University (XIAMEN facility), which is the first triple beam system and the only in-running <jats:italic>in-situ</jats:italic> irradiation facility with TEM in China. In this work, we conducted the first high-temperature triple simultaneous ion beams irradiation experiment with TEM observation using the XIAMEN facility. The responses to <jats:italic>in-situ</jats:italic> triple-ion beams irradiation in austenitic steel 304L SS and ferritic/martensitic steel CLF-1 were studied and compared with the results in dual- and single-ion beam(s) irradiated steels. Synergistic effects were observed in MSIB irradiated steels. Helium was found to be critical for cavity formation, while hydrogen has strong synergistic effect on increasing swelling.</jats:p>

<jats:p>A nano-twinned microstructure was found in amorphous SiC after high-temperature annealing. Grazing incidence x-ray diffraction, high-resolution transmission electron microscopy, and electron diffraction were performed to characterize the microstructure and phase transition in the recrystallization layer. After 1500 °C or 2-h annealing, 3C-SiC grains and numerous stacking faults on the {111} planes were visible. Some 3C-SiC grains have nano-twinned structure with {011} planes. Between the nano-twinned 3C-SiC grains, there is a stacking fault, indicating that the formation mechanisms of the nano-twinned structure are related to the disorder of Si atoms. The increase in the twin thickness with increasing annealing temperature demonstrates that the nano-twinned structure can sink for lattice defects, in order to improve the radiation tolerance of SiC.</jats:p>